The invention relates to means for connecting at least two filter cartridges.
For purifying the lubricating oil of internal-combustion engines, there are normally used so-called tubular filter cartridges which consist of a filter element in a suitable filter material, for example radially pleated filter paper, and whose front ends are sealingly embraced by end discs. Sleeve-shaped, perforated supporting guards, which are attached to the inside and outside circumferences of the filter element, serve for stiffening the cartridge. More especially in the case of motorcycle internal-combustion engines, the space available for the installation of the oil filters is often so small that the installation and removal of the filter cartridge, which is necessary for the filtering process and has a certain length, is only rendered possible in that the internal-combustion engine is released from its holding support or other units surrounding the oil filter are dismantled.
In connection with an oil filter whose filter cartridge cannot be removed directly vertically from the filter housing because of the confined space conditions, it is known from GB PS No. 542 339 to provide two filter cartridges which, being axially arranged in series, are rigidly connected together by a connecting means. When these rigidly connected filter cartridges are removed, the upper filter cartridge is grasped and is pulled vertically from the filter housing, during which process the lower filter cartridge is also taken along. Once the upper filter cartridge has been pulled fully from the filter housing, so that the lower filter cartridge projects from the edge of the filter housing and can be grasped, the upper filter cartridge has to be broken away in order to allow the second filter cartridge to be pulled completely from the filter housing.
This procedure during the removal of the two filter cartridges is complicated and has to be carried out with great care, for the danger exists that, when the first filter cartridge is broken off, the second filter cartridge will slip back into the filter housing and can no longer be grasped and removed or this can only be done with an additional effort.
Furthermore, it is impossible to install the two completely joined filter cartridges.